MegaTraveller: Aliens 1 - Vilani and Vargr (the Coreward Races)(MT-ALIENS1)
Sourcebook for the
Vargr, a major race, and the
Vilani,. a major race of
humaniti.
Known colloquially as "Cogs & Dogs".Published by WHO, WHEN. Current to 1120 Imperial.

MegaTraveller: Aliens 2 - Solomani and Aslan (the Rimward Races)(MT-ALIENS2)
Sourcebook for the
Solomani, a major race of
humaniti, and the
Aslan,. a major race.
Known colloquially as "Rats &amp Cats".Published by WHO, WHEN. Current to 1120 Imperial.

MegaTraveller: Aliens 3 & 4 (never published)
Interestingly, two further sourcebooks were planned but never published. They were tentatively entitled "MegaTraveller: Aliens 3 - Droyne and Zhodani (the Psionic Races)" and "MegaTraveller: Aliens 4 - Hivers and K'kree (the Weird Ones)".
Colloquially, they may well have become known as "Bugs & Thugs" and "Moonies & Loonies" - but I would never suggest such a thing, of course. ;-)